The FDA has approved the radioactive diagnostic agent florbetapir (Amyvid) for evaluation of the causes of cognitive decline, including Alzheimer’s disease, according to Eli Lilly, developer of the compound.
Florbetapir is used in conjunction with positron emission tomography to evaluate the burden of amyloid plaques in the brain, according to Daniel Skovronsky, MD, PhD, the company’s brand development leader for the product.
The main value of the test, Skovronsky told MedPage Today during a telephone media briefing, will be in ruling out Alzheimer’s disease.
Although amyloid plaques are considered to be a hallmark of Alzheimer’s, he said, they also appear in other forms of dementia and in the course of normal aging.
And many patients diagnosed with Alzheimer’s – as many as one in five – do not show amyloid plaques during autopsy, he noted.
A florbetapir scan showing few or no amyloid plaques would rule out the disease, he said, adding “in those patients, physicians can then focus on looking for other causes of dementia.”
The approval of the product is a “great advancement in nuclear medicine practice,” said Edward Coleman, MD, of Duke University Medical Center.
“It may help give physicians additional information when evaluating patients with cognitive decline,” he told reporters during the media briefing
Coleman cautioned that the compound does add to a patient’s cumulative exposure to radiation.
He also added that, in response to FDA concerns about the reliability of the test, the results of the PET scan should only be interpreted by a physician who has gone through a “reader training program” that’s now available online.
The company said florbetapir was evaluated in three main clinical studies that examined healthy adult patients, patients with a range of cognitive disorders, and some terminally ill patients who had agreed to have their brains evaluated post mortem.
In one study, the company said in a release, post-mortem cortical amyloid burden was highly correlated with median scores on the florbetapir scans, with a correlation coefficient of r=0.78 and a significance level of P
Florbetapir scans had a median sensitivity of 92% and specificity of 95% for readers who had in-person training and 82% and 95%, respectively, for readers trained online.
The most common patient adverse effect in the clinical trials was headache, reported by 1.8% of participants, followed by musculoskeletal pain, fatigue, and nausea.
Michael Smith, North American Correspondent, MedPage Today